The role of pH in heavy metal detoxification by biosorption from aqueous solutions containing chelating agents

Abstract

The high level of toxic metal pollution in the environment is a result of increased human activities. The hydrogen ion concentration of solutions has been known to affect reactions in solutions. The role of pH in As(V), Pb(II) and Hg(II) ions detoxification by bio-sorption from aqueous solutions using coconut fiber and sawdust waste biomass, containing chelating agents was studied. pH characteristically influenced adsorption. Maximum adsorption occurred at pH 2 and 12 whereas minimum adsorption occurred at pH 6-8. Modification of the adsorbent by carboxymethylation and thiolation decreased the absorption capacity. As(V) metal ion was adsorbed more than Hg(II), then followed by Pb(II) ion. A model was proposed for the action of pH on the adsorption pattern of the metal ions on the adsorbents used. Desorption studies was investigated using NaOH and H2PO4. Therefore, these results can serve
as parameters for design of treatment plants for heavy metal detoxification using agricultural byproducts, such as sawdust and coconut fiber.